1. Field of the Invention
Hangers for adjustably slidable mounting of electric lamps.
2. Description of the Prior Art
The slidable adjustable mounting of electric lamps is desirable in many instances where illumination is required at diverse areas within the same general location. Typical instances where it is desirable to move, shift or reposition lighting facilities include effect lighting, spot lighting, area lighting and work lighting in homes, and activities in drafting rooms, machine shops, home workshops, dentist's and doctor's offices, hospital operating rooms, various types of factories, especially process control rooms or laboratories of chemical plants and assembly lines of automobile and appliance factories, etc. Other activities such as reading or writing, e.g. at a desk or table, in a library or study, etc. often require a periodic shifting of the light source or of the concentration of the lighting.
Some prior art installations have entailed the use of bus bars and specially designed contacts for use with bus bars, which required the services of a skilled and highly paid electrician for installation and servicing. Other prior art has contemplated channel members running along a wall or ceiling. Typical prior art devices are disclosed in U.S. Pat. Nos. 507,364; 1,757,617; 2,858,381; 3,718,816 and 3,885,147.
A major problem with prior art installations, commonly known as "track" lighting, was the presence of bare elongated conductors to which electrical connectors were designed to be detachably physically and electrically engaged. Considerable ingenuity and expense was required to make certain that such engagement was secure, as well as quickly and easily manipulatable, inasmuch as the tracks usually were situated in locations, such as ceilings, where accidental disengagement could be dangerous to occupants of a room, and where access to the tracks for installation, change or renewal of a lamp, might be precarious. Moreover, the presence of electrified bare conductors, even though shielded, represented a dangerous situation which restricted their use to areas that were normally inaccessible to children and accessible only with difficulty to adults.